Thursday, February 13, 2014

VOA Radiogram for Feb. 15-16

VOA Radiogram continues to experiment with simultaneous text and image transmission. It makes a godawful racket on the audio channel, but it works.  Here is the image transmitted last week, cleaned up by combining pixels from the upper and lower sidebands as sent on 5745 kHz.




From Kim Andrew Elliott:

Hello friends,

Happy World Radio Day. See http://www.worldradioday.org/

About 25 cm of snow is on the ground here in Arlington, Virginia. The federal government is closed, which means I can work on VOA Radiogram at home rather than at the office.

On VOA Radiogram during the weekend of 15-16 February 2014 (program 46), we will try another simultaneous transmission of text and an image. This time it will be text in MFSK32 centered on 2000 Hz, and the image in MFSK64 centered on 1000 Hz.

Here is the procedure:

1) Have two instances of Fldigi running.

2) Turn on the RxID (green) on both instances of Fldigi.

3) After the mode changes to MFSK64, turn off the RxID on your
second instance of Fldigi.

4) Enjoy

After program 46, we will take a break from simultaneous text and image transmissions. It's a lot of extra work for me to produce, and a lot of extra work for you to decode.

Program 46 will also include Chinese characters, transmitted as MFSK32 and later (and faster) as MFSK64L. I would grateful of recordings of the digital transmission of the Chinese characters, especially in the presence of interference or local noise.

Here is the lineup for VOA Radiogram, program 46, 15-16 February 2014:

 1:35  MFSK32: Program preview
 3:50  MFSK32/64: Press freedom index with simultaneous image*
10:49  MFSK32: Bing accused of censorship, with image
16:41  MFSK32: Hacking at Sochi Olympics, with image
22:09  MFSK32: Sample of VOA Chinese text**, with image
25:22  MFSK64L: Same sample of VOA Chinese text
27:28  MFSK32: Closing announcements

*Run two instances of Fldigi, starting with RxID on in both
instances. Test will be centered on 2000 Hz, the image on 1000
Hz.

**Use UTF-8 character set. In Fldigi: Configure > Colors & Fonts
> Rx/TX > Set top (white) box to UTF-8.

Please send reception reports to radiogram@voanews.com

From your reports, it appears that last weekend's simultaneous text and image transmissions were largely successful. Thanks for those reports, which I'll be answering in the next couple of days.


Kim

Kim Andrew Elliott
Producer and Presenter
VOA Radiogram
voaradiogram.net

VOA Radiogram transmission schedule
(all days and times UTC):
Sat 0930-1000 5745 kHz
Sat 1600-1630 17860 kHz
Sun 0230-0300 5745 kHz
Sun 1930-2000 15670 kHz

All via the Edward R. Murrow transmitting station in North Carolina.

Kim

voaradiogram.net